Abstract
Antimicrobial resistance (AMR) is a pressing crisis for global health. At the front lines of detecting AMR are clinical laboratories, which perform antimicrobial susceptibility testing (AST). In recent years, the ability of laboratories to conduct this testing in the United States has been challenged by changing interpretive standards and increased regulation surrounding laboratory testing, most recently U.S. Food and Drug Administration (FDA) regulation of laboratory-developed tests. In early 2025, the FDA recognized many breakpoints published by the Clinical Laboratory Standards Institute, including for microorganisms that represented an unmet need. This unprecedented step heralds a pragmatic approach to AST by the FDA and is a major win for laboratories, clinicians, and patients in the United States and globally. In this commentary, we discuss these changes and the impact on clinical laboratories.